1. Field of the Invention
This invention relates to a process for introducing volatile additives into a molten metal and more particularly to treating molten iron with magnesium to produce nodular iron.
The invention also relates to apparatus useful in this method.
2. Description of Prior Art
Because of the explosive reaction between pure magnesium and molten iron, most treatments to produce nodular iron have aimed at taming the reaction by using magnesium alloys or delaying contact of the molten iron with magnesium.
One commercial solution, aimed at using pure magnesium, has been to employ a special tiltable converter with a refractory-walled receptacle for magnesium built into one side of it. The magnesium is loaded into the chamber by a closable access port through the wall and refractory lining of the vessel. Passages from the chamber to the interior of the converter allow entrance of molten iron and escape of reaction products into the body of the molten iron. For charging the magnesium, the converter is tilted on its side, with the chamber above the level of the metal. To carry out the treatment, the vessel is tilted into the upright position, submerging the chamber. The position of the entry and escape openings are said to permit a controlled flow of metal into and through the chamber and to insure a quiet and efficient iron-magnesium reaction enabling high receoveries.
This method has the disadvantage that a special converter is required in which the refractory wall is interrupted by the loading port. Also, the converter has to be manipulated between the upright and the tilted position and back again during each loading cycle. And, access for cleaning the entrance and outlet openings is hampered by the magnesium chamber being part of the vessel.